Temperature signals in seed germination

Plant Biology The switch between seed dormancy and germination in Arabidopsis thaliana is regulated by the balance between the hormones abscisic acid (ABA) and gibberellin (GA). Low temperatures are known to cause an increase in GA synthesis and receptor abundance, thereby increasing the probability of germination. Topham et al. studied the integration of temperature signals and determined that the embryo radicle is enriched for factors involved in hormone signaling, synthesis, and degradation. A clear spatial pattern emerged whereby ABA and GA pathway components were broadly separated into different cell types. This spatial separation and control over transport of hormones between cells facilitates processing of fluctuating temperature inputs and increases their propensity to break seed dormancy, compared with signals from continuous cold exposure. This is hypothesized to ensure accurate timing of seedling establishment through recognition of environmental temperature oscillations. Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1704745114 (2017).